Converter System for an Active Noise Compensation Apparatus

ABSTRACT

There is provided a transducer system for an active noise compensation apparatus, which has a first end at the ear side and an electroacoustic transducer. The electroacoustic transducer has a diaphragm system and a magnet system, wherein the central region of the diaphragm system is curved towards the magnet system and is in the form of an inverted calotte. A sensor microphone is arranged in a volume between the first end and the region of the curvature of the diaphragm system.

The present invention concerns an electroacoustic transducer system foran active noise compensation apparatus and a headset having such atransducer system.

Conventional active noise compensation apparatuses have a reproductiontransducer system with a sensor microphone which is arranged between theelectroacoustic transducer and the ear of a wearer, in particular asclosely as possible to the ear of the wearer. The sound recorded by thesensor microphone is used for active noise compensation.

DE 1 876 054 discloses a diaphragm for an electroacoustic transducer,wherein a portion of the diaphragm is curved in a cup shape.

U.S. Pat. No. 5,182,774 discloses a headset with an active noisecompensation apparatus. In that case a sensor microphone is arrangedbetween a transducer system and an ear of a wearer so that themicrophone projects mechanically and there can be a certain risk ofinjury.

Therefore the object of the present invention is to provide a transducersystem and/or an active noise compensation apparatus which has a reducedrisk of injury.

That object is attained by a transducer system for an active noisecompensation apparatus as set forth in claim 1 and by a headset as setforth in claim 6.

There is thus provided a transducer system for an active noisecompensation apparatus, which has a first end at the ear side and anelectroacoustic reproduction transducer. The electroacoustic transducerhas a diaphragm system and a magnet system, wherein the central regionof the diaphragm system is curved towards the magnet system and is inthe form of an inverted cup. A sensor microphone is arranged in theregion of the curvature of the diaphragm system.

The invention concerns a transducer system for an active noisecompensation apparatus, wherein an (electro)acoustic transducer has aninverted cup and the sensor microphone as viewed from the ear isarranged in front of the electroacoustic transducer or the diaphragmsystem, that is to say the sensor microphone is arranged axially spacedin relation to the diaphragm system. That has in particular theadvantage that the structural height of an active noise compensationapparatus is decreased and a risk of injury is reduced. The sensormicrophone is thus arranged in the region between the inverted cup andan ear of a wearer. Such an arrangement means that the sensor microphonecan be disposed very close to the ear of a wearer. That is particularlyadvantageous for active noise compensation. In that case the cup of theacoustic transducer is of such a configuration that it is curved towardsthe (axially spaced) magnet system. Thus the sensor microphone can beplaced within the free volume which is afforded by the arrangement ofthe inverted cup, afforded by the inward curvature of the diaphragm.

Further configurations of the invention are set forth in the appendantclaims.

The invention is described in greater detail hereinafter with referenceto the accompanying drawing in which:

FIG. 1 shows a diagrammatic view in section of an electroacousticreproduction transducer according to the invention.

FIG. 1 shows a diagrammatic view in section of an electroacoustictransducer system. Shown here is in particular an electroacousticreproduction transducer 10 for the reproduction of audio signals, whichcan be used for example in an active noise compensation apparatus. Theelectroacoustic transducer 10 has a first end at the ear side, and asecond end 12 remote from the ear, as well as a diaphragm system 20 withan inverted cup 30. Provided in the free volume which is afforded by theinward curvature of the diaphragm system by virtue of the arrangement ofthe inverted cup 30 (that is to say in the volume between the invertedcup 30 and the first end 11 or the ear of the wearer) is a sensormicrophone 40 for recording noise or sound, which is required for activenoise sound compensation. The transducer 10 also has a magnet system 50and an opening 60, remote from an ear, in the second end 12.

An active noise compensation apparatus is disclosed in patentspecification EP 0 737 022 B1, the disclosure of which is referred tofor the purposes of disclosure of the invention. In particular thedisclosure of the principle of the active noise compensation apparatus,as described with reference to FIGS. 1 through 3 and in paragraphs[0019] through [0028], with the reproduction transducer and the sensormicrophone, is referred to for the purposes of disclosure. Thecompensation circuit is shown in FIG. 3 and described in paragraph[0028], which is also referred to for the purposes of disclosure.

The holes or openings 60 in the second end remote from the ear serve toprovide that the air in the volume between the inverted cup 30 and thehousing 10 can escape outwardly. Preferably the spacing between thesensor microphone 40 and the inverted cup 30 should be as small aspossible without the microphone 10 and the inverted cup 30 colliding atmaximum deflection. A spacing which is as small as possible between thesensor microphone 40 and the inverted cup 30 provides that the transittime is reduced so that the 180° phase shift of the recorded sound,which is required for active noise compensation, can be better achieved.The reproduction transducer serves to reproduce the noise-compensatedaudio signal, in which respect noise compensation is effected asdescribed in EP 0 737 022 B1, FIG. 3, paragraph [0028], on the basis ofthe noise or sound recorded by the sensor microphone.

Thus the sensor microphone 40 is arranged directly in front of theinverted cup 30. In that respect the sensor microphone 40 is preferablyheld by a resonator (not shown).

The arrangement described with reference to FIG. 1 of the inverted cup30 and the sensor microphone 40 provides that the transmission distancebetween the electroacoustic transducer 10 and the sensor microphone ormeasuring microphone 40 for active noise sound compensation can beconsiderably reduced.

Although FIG. 1 shows an orientation of the sensor microphone 40, thatis substantially perpendicular to an ear, the sensor microphone can alsobe arranged at any other angle.

The magnet system 50 is preferably arranged on the outside as shown inFIG. 1 so that the inverted cup 30 has space therebetween. As analternative thereto the magnet system can also be arranged inwardly. Insuch a case however the magnets are preferably shaped to correspond tothe curvature of the inverted cup 30. The shaping of the magnet systemcan be used for acoustic dimensioning.

1-6. (canceled)
 7. An electroacoustic transducer system for an activenoise compensation apparatus comprising: a first end at the ear side; anelectroacoustic reproduction transducer which has a diaphragm system anda magnet system, wherein a central region of the diaphragm system iscurved towards the magnet system and is in the form of an invertedcalotte; and a sensor microphone for recording interference noisearranged in a volume between the first end and the region of thecurvature of the diaphragm system.
 8. A transducer system as set forthin claim 7 wherein the directivity of the sensor microphone is directedtowards the first end of the transducer system.
 9. A transducer systemas set forth in claim 7 wherein the spacing between the sensormicrophone and the inverted calotte is such that the sensor microphoneand the inverted cup do not touch even at maximum deflection of theinverted cup.
 10. An active noise compensation apparatus comprising atransducer system as set forth in claim
 7. 11. A headset comprising atransducer system as set forth in claim 7 and/or an active noisecompensation apparatus comprising a transducer system as set forth inclaim
 7. 12. Headphones comprising a transducer system as set forth inclaim 7 and/or an active noise compensation apparatus as set forth inclaim 7.